Science Advisory Report 2009/058
Potential Recovery Assessment for the Misty Lake stickleback (Gasterosteus spp.) pair
Summary
- Misty Lake supports two separate forms of stickleback, usually referred to as a “stickleback pair.” Threats to population persistence of the different forms include alien species, road run-off, logging, water withdrawal and climate change. Introduction of alien species is considered the most serious current threat to the pair populations.
- Current estimates of the lake and stream populations are highly uncertain and range from the low thousands to tens of thousands. A population size of 10,000 mature individuals for each inlet, outlet and lake form are recommended as appropriate targets for Misty Lake stickleback. Given the uncertainty in the population estimates and the high cost of error, a precautionary threshold for allowable harm of 5% is likely reasonable.
- Habitat threats and the potential for collapse of the pair populations from inter-breeding (hybridization) is the most important conservation risk. Identification of habitat requirements for survival of the pair should consider the role of habitat in maintaining reproductive isolation between the pair.
- Because of the importance of habitat in maintaining reproductive isolation of each form, potential critical habitat includes the lake, the full length of the inlet stream, 2.3 km of the outlet stream and all ephemeral streams.
- There remains high uncertainty on the amount of riparian habitat necessary for the survival of the species pair. Given this uncertainty, riparian buffer widths of 15-30 m around the lake and the inlet and outlet streams are recommended. Additional study of the relationship between stickleback pair survival needs and riparian functions may help to confirm the identified critical habitat in the future.
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